Reconciliation of Net Income/(Loss) to Net Income/(Loss) Available to Common Shareholders (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net Income (Loss) Attributable to Parent	$ 537	$ 576	$ 1,449	$ 1,380
Dividends, Preferred Stock, Cash	(16)	(9)	(48)	(28)
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	(2)	(4)	(5)	(9)
Net Income (Loss) Available to Common Stockholders, Basic	$ 519	$ 563	$ 1,396	$ 1,343
Average basic common shares	513,010	527,402	516,970	529,429
Stock options	2,000	2,000	2,000	2,000
Restricted stock	4,000	4,000	4,000	4,000
Weighted Average Number of Shares Outstanding, Diluted	518,677	533,230	522,634	535,222
Net income/(loss) per average common share - diluted	$ 1.00	$ 1.06	$ 2.67	$ 2.51
Earnings Per Share, Basic	$ 1.01	$ 1.07	$ 2.70	$ 2.54